说明：  定义一个20元素的整数数组，通过键盘输入该数组，并用排序法将数组从大到小排序，排序后，按照每行5个元素进行输出 排序法可选择：擂台法，冒泡法，选择法
(Define an integer array of 20 elements, input the array through the keyboard, and sort the array from large to small with sorting method. After sorting, output according to 5 elements per line Sorting method can be selected: challenge arena method, bubble method, selection method)